TURRITELLIDAE 141 



but usually has spiral cords only on the base and one just above the suture, 

 and has about i8 to lo axial, rounded ribs per whorl. Some specimens show 

 fine, spiral, incised lines. Common from 1 6 to 60 fathoms. 



Tachyrhynchiis lacteolum Carpenter Milky Turret-shell 



Alaska to Lower California. 



% inch in length, similar to erosinn, but % as wide as long, and the cords 

 between sutures are finely beaded. The beads are arranged more or less in 

 axial rows. The last third of the body whorl bears weak, non-beaded spiral 

 cords. This species differs from reticulatum in its smaller size, less slender 

 shape, less convex whorls, and much finer sculpturing. 



Genus Turritella Lamarck 1799 

 Turritella acropora Dall Boring Turret-shell 



Plate 21] 



North Carolina to Florida, Texas and the West Indies. 



1 inch in length, resembling exoleta, but with convex whorls, and with 

 numerous, fine, spiral threads a few of which, at the periphery, are slightly 

 larger than the others. There is a very weak series of riblets just below the 

 suture. Color yellowish to brownish orange. Common just offshore. 



T. variegata Linne, the Variegated Turret-shell (pi. 2ii) (West Indies), 

 is similar, but up to 4 inches in length, with flat-sided whorls, and is mottled 

 with mauve, white and dark-brown. Common. 



Turritella exoleta Linne Eastern Turret-shell 



Plate 2ih 

 South half of Florida and the West Indies. 



2 inches in length, long, slender and with a sharp apex. Each whorl with 

 a large, coarse cord above and below, with the part between the cords con- 

 cave and occasionally crossed by microscopic, arched, brown, scale-like 

 lamellae. Base of shell concave. Color glossy-white to cream with sparse, 

 axial flammules of light yellow-brown. Moderately common from i to 100 

 fathoms. This species is placed in the subgenus Torcula Gray 1847. 



Turritella cooperi Carpenter Cooper's Turret-shell 



Plate 20g 



Monterey, California, to Lower California. 



I to 2 inches in length, 17 to 20 slightly convex whorls. Base concave. 

 Columella and outer lip fairly fragile. AVhorls with 2 or 3 small, spiral cords 



